public class Circle extends Shape{
    //中心点
    private Point center;
    //半径
    private double r;
    public Circle(Point center,double r){
        this.center = center;
        this.r = r;
    }
    @Override
    public void draw(){
        System.out.println("draw circle at " + center.toString()+" with r " + r + ",using color: "+ getColor());
    }
    public double area(){
        return Math.PI*r*r;
    }
}